The definitive book about the incident is "Freefall" by William & Marilyn Mona Hoffer (ISBN 0-312-02919-5). Couple of points:
1. You can pressurise most jets using ram air & the cabin altitude limiters will also help retain pressurisation.
2. There are battery back-ups for the Avionics on the 767 & I beleive the RAT can also power a hydraulically-driven generator. (Sorry I don't have my 767 schematics at home).
I do know that the whole fuel system was redesigned after Gimli with particular emphasis on making sure you couldn't mix imperial (pounds) with metric (kilograms) between the Fuel Quantity Computer and the EICAS and thus inadvertantly show a "correct" fuel load when under half had been uplifted!